It is known from documents US 2008/0310692 A1, U.S. Pat. No. 7,465,560 B2 and EP 2,122,326 B1 to determine the biological species of a bacterium by studying the transmission pattern obtained by the diffusion of incident photons by the bacteria, the bacterium being on a substrate.
However, such a transmission pattern cannot be obtained when the substrate includes blood, since the low transmission coefficient of blood prevents obtaining the diffraction pattern. Indeed, in the aforementioned documents, image obtainment in transmission does not work when the substrate and its holder are opaque.